Pressure relief valve with rotating damper

ABSTRACT

A combustible gas burner includes gas flow conduit or a housing having an outlet and a pressure relief valve. The pressure relief valve includes a valve seat at the outlet, a valve body and a valve body rotator. The valve body is configured to engage the valve seat and move along an axis relative to the valve seat in response to a pressure at the outlet to regulate the flow of combustible gas through the outlet. The valve body rotator is configured to rotate the valve body about the axis in response to movement of the valve body along the axis relative to the valve seat.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is a Section 371 National Stage Application ofInternational Application No. PCT/US2014/011780, filed Jan. 16, 2014 andpublished as WO/2014/113529 on Jul. 24, 2014, in English, which claimsthe benefit of U.S. Provisional Application Ser. No. 61/754,219 filedJan. 18, 2013 under 35 U.S.C. § 119(e), the contents of which are herebyincorporated by reference in their entirety.

BACKGROUND

There are many occasions in which waste gasses are disposed of using aflare stack burner. Such burners having conventionally utilized a flaretip comprising a valve body, such as a Coanda body, that is either freefloating or spring-loaded against an outlet or valve seat of a gas pipe.Pressurized waste gas lifts the valve body off the valve seat to form avariable opening through which the waste gas is discharged and ignitedby a pilot burner to dispose of the waste gas.

The exit velocity of the gas through the variable opening changes inresponse to the displacement of the valve body off the valve seat. Thisoccurs due to the variable load applied to the valve body by the spring.As pressure increases, the valve body is displaced further from thevalve seat.

The exit velocity of the gas past the spring-loaded flare tip increasesas the square of the pressure. This can place significant volumetric gasflow limitations on spring-loaded flare tips due to exit velocitylimitations (e.g., 400 ft/s) commanded by some environmental standards.

Additionally, at low pressures, conventional flare tips are known toproduce “chatter.” Chatter occurs when the gas produces enough pressureto lift the valve body off the valve seat, but not enough pressure tomaintain the displacement of the valve body from the valve seat.Instead, the valve body repeatedly lifts off the valve seat and thendrops back onto the valve set in a rapid manner, causing undesirablechatter noise. Additionally, such chatter can potentially damage to thevalve seat.

SUMMARY

Some embodiments of the invention are directed to a combustible gasburner. In some embodiments, the combustible gas burner includes gasflow conduit or a housing having an outlet and a pressure relief valve.The pressure relief valve includes a valve seat at the outlet, a valvebody and a valve body rotator. The valve body is configured to engagethe valve seat and move along an axis relative to the valve seat inresponse to a pressure at the outlet to regulate the flow of combustiblegas through the outlet. The valve body rotator is configured to rotatethe valve body about the axis in response to movement of the valve bodyalong the axis relative to the valve seat. The rotational movement ofthe valve body can reduce or eliminate chatter.

In some embodiments, the burner comprises a shaft attached to the valvebody, one or more bushing supports, each having a fixed positionrelative to the conduit, and one or more bushings, through which theshaft extends, each bushing supported by one of the bushing supports andconfigured to maintain the shaft in general alignment with the axis. Insome embodiments, the valve body rotator comprises a rod having a firstend coupled to the shaft and a second end coupled to one of the bushingsupports. In some embodiments, rotation of the valve body and the shaftabout the axis is driven using the rod responsive to movement of thevalve body along the axis relative to the valve seat in response topressure changes or gas flow changes at the outlet. In some embodiments,the rod is placed at an angle relative to the axis, and the angle ischanged in response to moving the valve body along the axis relative tothe valve seat in response to pressure or gas flow changes at theoutlet.

In some embodiments of the burner, the valve body engages the valve seatto place the pressure relief valve in a closed mode when the pressure atthe outlet is below a threshold pressure. In some embodiments,pressure-driven movement of the valve body along the axis displaces thevalve body from the valve seat to place the pressure relief valve in anopen mode when the pressure at the outlet is above the thresholdpressure. In some embodiments, the combustible gas is discharged throughthe outlet at a substantially constant velocity when the pressure reliefvalve is in the open mode. In some embodiments, the valve body rotatoris within the conduit. In some embodiments, the valve body rotator isconfigured to accelerate the rotation of the valve body about the axisin response to fluctuations in the pressure at the outlet. In someembodiments, the valve body rotator is configured to vary an amount ofrotation of the valve body per unit length of movement of the valve bodyalong the axis relative to the valve seat based on a distance the valvebody is displaced from the valve seat.

In some embodiments, the valve body rotator is configured to vary anamount of rotation of the valve body per unit length of movement of thevalve body along the axis relative to the valve seat based on a distancethe valve body is displaced from the valve seat. In some embodiments,the valve body rotator is configured to decrease the amount of rotationof the valve body per unit length of movement of the valve body alongthe axis relative to the valve seat as the distance the valve body isdisplaced from the valve seat increases. In some embodiments, the valvebody rotator is configured to increase the amount of rotation of thevalve body per unit length of movement of the valve body along the axisrelative to the valve seat as the distance the valve body is displacedfrom the valve seat decreases.

Some embodiments of the burner comprise a shaft attached to the valvebody, one or more bushing supports, and one or more bushings throughwhich the shaft extends. In some embodiments, each bushing support has afixed position relative to the conduit or housing. Each bushing issupported by one of the bushing supports and is configured to maintainthe shaft in general coaxial alignment with the axis. In someembodiments, the burner comprises at least two bushing supportsdisplaced from each other along the axis. In some embodiments, thebushing supports are each attached to the conduit or housing.

In some embodiments, the valve body rotator comprises a rod having afirst end coupled to the shaft and a second end coupled to one of thebushing supports. The rod drives rotation of the shaft and the valvebody responsive to movement of the valve body along the axis relative tothe valve seat. In some embodiments, the rod is displaced at an anglerelative to the axis, and the angle changes in response to movement ofthe valve body along the axis relative to the valve seat.

In some embodiments, the burner includes a pilot burner configured toignite the combustible gas discharged through the outlet.

Some embodiments of the invention are directed to a pressure reliefvalve or gas flow regulator comprising a valve body and a valve bodyrotator. The pressure relief valve may be installed in any suitableconduit or housing to provide pressure relief when the pressure withinthe conduit or housing exceeds a cracking pressure of the valve. In someembodiments, the valve body is configured to engage a valve seat andmove along an axis relative to the valve seat in response to a pressurewithin the conduit or housing to which the pressure relief valve ismounted. In some embodiments, the valve body rotator is configured torotate the valve body about the axis in response to movement of thevalve body along the axis relative to the valve seat. Displacement ofthe valve body from the valve seat forms a variable opening throughwhich gas or fluid within the conduit or housing is discharged.Embodiments of the pressure relief valve include those described hereinwith regard to the combustible gas burner embodiments.

Additional embodiments are directed to a method of regulating a flow ofcombustible gas through an outlet of conduit or a housing of the burner.In some embodiments, a valve body is moved along an axis relative to avalve seat located at the outlet in response to changes in pressure orthe gas flow at the outlet. The valve body is rotated about the axisresponsive to the moving of the valve body along the axis relative tothe valve seat using a valve body rotator.

In some embodiments, the valve body engages the valve seat when thepressure at the outlet is below a threshold pressure, and the valve bodyis displaced along the axis from the valve seat when the pressure at theoutlet is above the threshold pressure. In some embodiments, combustiblegas is discharged through the outlet at a substantially constantvelocity when the valve body is displaced from the valve seat and thepressure at the outlet is above the threshold pressure. In someembodiments, the combustible gas discharged through the outlet isignited using a pilot burner. In some embodiments, an amount of rotationof the valve body per unit length of movement of the valve body alongthe axis relative to the valve seat is varied based on a distance thevalve body is displaced from the valve seat using the valve bodyrotator.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter. The claimed subject matter is not limited to implementationsthat solve any or all disadvantages noted in the Background.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are simplified block diagrams of a combustible gas burnerrespectively in closed and open modes, in accordance with embodiments ofthe invention.

FIG. 3 is a simplified top view of a valve body rotator of a pressurerelief valve of the combustible gas burners of FIGS. 1 and 2.

FIGS. 4 and 5 are isometric views of a combustible gas burner withportions shown in cross-section and a pressure relief valve respectivelyin closed and open modes.

FIGS. 6 and 7 are side cross-sectional views of the burner of FIGS. 4and 5, respectively.

FIGS. 8 and 9 are bottom plan views of the burner of FIGS. 4 and 5,respectively.

FIG. 10 is a flowchart illustrating a method of regulating a flow ofcombustible gas through an outlet of conduit of a burner in accordancewith embodiments of the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the invention are described more fully hereinafter withreference to the accompanying drawings. Elements that are identifiedusing the same or similar reference characters refer to the same orsimilar elements. The various embodiments of the invention may, however,be embodied in many different forms and should not be construed aslimited to the embodiments set forth herein. Rather, these embodimentsare provided so that this disclosure will be thorough and complete, andwill fully convey the scope of the invention to those skilled in theart.

Specific details are given in the following description to provide athorough understanding of the embodiments. However, it is understood bythose of ordinary skill in the art that the embodiments may be practicedwithout these specific details. For example, circuits, systems,networks, processes, frames, supports, connectors, motors, processors,and other components may not be shown, or shown in block diagram form inorder to not obscure the embodiments in unnecessary detail.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, if an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. Thus, a first element could be termed a secondelement without departing from the teachings of the present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Embodiments of the invention may also be described using flowchartillustrations and block diagrams. Although a flowchart may describe theoperations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be re-arranged. A process is terminated when itsoperations are completed, but could have additional steps not includedin a figure or described herein.

It is understood that one or more of the blocks (of the flowcharts andblock diagrams) may be implemented by computer program instructions.These program instructions may be provided to a processor circuit, suchas a microprocessor, microcontroller or other processor, which executesthe instructions to implement the functions specified in the block orblocks through a series of operational steps to be performed by theprocessor(s) and corresponding hardware components.

FIGS. 1-3 illustrate embodiments of a combustible burner 100, such as aflare stack burner, formed in accordance with one or more embodiments ofthe invention. FIGS. 1 and 2 are simplified block diagrams of acombustible gas burner 100 respectively in closed and open modes, inaccordance with embodiments of the invention. FIG. 3 is a simplified topview of a valve body rotator of a pressure relief valve of thecombustible gas burners of FIGS. 1 and 2.

In some embodiments, the burner 100 includes gas flow conduit or ahousing 102 including an outlet 104, and a pressure relief valve or gasflow regulator (hereinafter “pressure relief valve”) 106. The pressurerelief valve 106 is generally configured to possibly seal and provide avariable opening at the outlet 104 of the gas flow conduit 102 toregulate the flow of combustible gas, which is represented by arrows 107(FIG. 2), through the outlet 104.

In some embodiments, the pressure relief valve 106 includes a valve body108 that engages a valve seat 110 at the outlet 104 when in a closedmode, as shown in FIG. 1 to form a seal at the valve seat 110 to preventor at least restrict the flow of gas through the outlet 104. In a flarestack burner, the valve body 108 may be referred to as a “flare tip.”The valve body 108 is configured to move along an axis 112 relative tothe gas flow conduit 102 and the valve seat 110 in response topressurized gas within the conduit 102, or at the outlet 104 to placethe pressure relief valve 106 in an open mode, in which the valve body108 is displaced from the valve seat 110, as illustrated in FIG. 2. Thisforms an opening, such an annular opening, between the valve body 108and the valve seat 110 that varies in response to the pressure at theoutlet 104.

In some embodiments, the pressure relief valve 106 comprises a valvebody rotator 114 that translates the pressure-driven movement of thevalve body 108 along the axis 112 into a rotation of the valve body 108,or other mass coupled to the valve body 108, about the axis 112, asindicated by arrow 116 in FIGS. 2 and 3. In other words, when thepressurized gas flow within the conduit 102 exceeds a threshold pressure(i.e., cracking pressure) on the valve body 108, the valve body 108rotates about the axis 112 as it moves along the axis 112 away from thevalve seat 110.

The mass of the valve body 108 controls the cracking pressure requiredto transition the valve body 108 from the closed mode (FIG. 1) to theopen mode (FIG. 2). The rotational inertia of the valve body 108operates as a damper that dampens the movement of the valve body 108along the axis 112 responsive to changes in the pressure of the gasflow. This rotational dampening prevents the valve body 108 from rapidlymoving along the axis 112 in response to pressure changes in the gasflow when the valve body 108 is engaging or is in close proximity to thevalve seat 110. This rotational dampening of the valve body 108eliminates or reduces the chatter that would otherwise occur if aconventional spring-loaded flare tip were used.

For instance, when the pressure of the gas within the conduit 102reaches the cracking pressure required to displace the valve body 108off the valve seat 110, the valve body rotator 114 causes the valve body108, or other attached mass, to rotate about the axis 112 as the valvebody 108 rises off the valve seat 110 and the gas flow 107 is dischargedthrough an opening between the valve body 108 and the valve seat 110 atthe outlet 104. Fluctuations in the pressure of the gas flow produce anacceleration to the rotation of the valve body 108 as the valve body 108moves further from the valve seat 110 during a pressure increase, ortoward the valve seat 110 during a pressure decrease. This rotation ofthe valve body 108 along with the relatively high rotational inertia ofthe valve body 108 relative to the foreseen gas flow pressures, preventsthe valve body 108 from producing the undesired chatter against thevalve seat 110 at gas flow pressures around the cracking pressure of thepressure relief valve 106.

In one exemplary embodiment, the valve body 108 is angularly displacedabout the axis 112 at an angle 118 (FIG. 3) of approximately 5 degreesas the valve body 108 lifts off the valve seat 110 a distance 119 (FIG.2) of approximately 0.030 inches. In some embodiments, the amount ofrotation 118 of the valve body per unit length of movement along theaxis 112 varies based on the distance 119 the valve body 108 isdisplaced from the valve seat 110. In some embodiments, the amount ofrotation of the valve body 108 about the axis 112 per unit length ofmovement along the axis 112 is greater when the valve body 108 is inclose proximity to the valve seat 110, than when the valve body 108 isdisplaced from the valve seat 110. This allows for a greater translationof the pressure on the valve body 108 to rotation of the valve body 108about the axis 112 when the valve body 108 is in close proximity to thevalve seat 110 in order to have the maximum effect on the reduction ofchatter between the valve body 108 and the valve seat 110. As the valvebody 108 moves away from the valve seat 110 along the axis 112, theamount of rotation of the valve body 108 in response to the movementalong the axis 112 is reduced and the valve body 108 operates more likea free floating valve body, in some embodiments.

Additional exemplary embodiments of the pressure relief valve 106 willbe described with reference to FIGS. 4-9. FIGS. 4 and 5 are isometricviews of the burner 100 with portions shown in cross-section and thepressure relief valve 106 respectively in closed and open modes. FIGS. 6and 7 are side cross-sectional views of the burner of FIGS. 4 and 5,respectively. FIGS. 8 and 9 are bottom plan views of the burner of FIGS.4 and 5, respectively.

The valve body rotator 114 can take on many different forms whileproviding the desired translation of gas flow pressure against the valvebody 108 in the direction of the axis 112 into a rotation of the valvebody 108 about the axis 112. In some embodiments, the valve body rotator114 comprises at least one bushing support 120 attached to the conduitor housing 102. Each of the bushing supports 120 includes a bushing 121through which a shaft 122, which is attached to the valve body 108,extends. In some embodiments, the shaft 122 is generally coaxial to theaxis 112. In some embodiments, the shaft 122 rotates with the rotationof the valve body 108 and moves along the axis 112 with the valve body108. In some embodiments, the one or more bushing supports 120 includearms 124 or other structure that are attached to the conduit or housing102. The arms 124 maintain the shaft 122 in coaxial alignment with theaxis 112 as the valve body 108 rotates and moves along the axis 112.

In some exemplary embodiments, the valve body rotator 114 includes a rod126 having an end 128 coupled to a distal end 130 of the shaft 122, andan end 132 coupled to one of the bushing supports 120 or the conduit102. In some embodiments, the ends 128 and 132 are each coupled to therespective distal end 130 of the shaft 122 and the conduit 102 orbushing support 120 through a ball joint 134. In some embodiments, theend 128 and the corresponding ball joint 134 is attached to the distalend 130 of the shaft 122 through a bell crank 136.

In some embodiments, the rod 126 is placed at an angle 138 relative tothe axis 112, as best shown in FIG. 7. The angle 138 affects the amountthe valve body 108 is rotated about the axis 112 in response to movementof the valve body 108 along the axis 112. In some embodiments, the angle138 increases as the valve body 108 is displaced from the valve seat 110along the axis 112. In some embodiments, the pressure relief valve 106includes one or more mechanical stops 140 that limit rotation of thebushing support 120 and/or limit movement of the valve body 108 alongthe axis 112.

As the end 132 of the rod 126 is fixed relative to the conduit 102,movement of the valve body 108 along the axis 112 relative to theconduit 102 causes an increase in the angle 138 and rotation of the bellcrank 136 about the axis 112 to which the end 132 of the rod 126 isattached, as shown in FIGS. 6 and 7. This in turn drives the rotation ofthe shaft 122 and the valve body 108 about the axis 112. The angle 138continues to increase as the valve body 108 is displaced further fromthe valve seat 110, thereby reducing the amount of rotation imparted tothe valve body 108 per unit of movement along the axis 112.

In operation, the burner 100 formed in accordance with embodimentsdescribed herein receives a flow of combustible gas, such as waste gas,at an inlet 142, which pressurizes the conduit or housing 102. When thepressure within the conduit 102 exceeds the cracking pressure, the valvebody 108 is displaced from the valve seat 110 along the axis 112 and aflow of gas 107 is discharged through an opening between the valve body108 and the valve seat 110, as shown in FIGS. 2, 5 and 7. During thispressure-driven displacement of the valve body 108 from the valve seat110, the valve body rotator 114 imparts a rotation to the valve body108. As mentioned above, in some embodiments, the rotation of the valvebody 108 per unit length of displacement of the valve body 108 from thevalve seat 110 along the axis 112 decreases as the valve body 108 movesfurther from the valve seat 110. In some embodiments, this reduction inthe angular rotation of the valve body 108 is caused by the variableangle 138 formed between the rod 126 and the axis 112, as discussedabove.

The variable opening formed between the valve body 108 and the valveseat 110 allows for the gas flow to pass over the valve body 108 and beignited by a suitable pilot burner 143 (FIGS. 1 and 2), in accordancewith conventional burners. In some embodiments, the valve body 108 has aCoanda shape, or other suitable shape.

The movement of the valve body 108 along the axis 112 provides asubstantially constant pressure for the gas flow 107 while accommodatingfor a wide range of volumetric gas flow rates. The cracking pressure forthe valve body 108 may be determined by the mass of valve body 108. As aresult, the velocity of the exiting gas flow 107 through the openingbetween the valve body 108 and the valve seat 110 may be tuned based onthe mass of the valve body 108 and the diameter of the outlet 104 of theconduit 102. In some embodiments, the mass of the valve body 108 may becustomized by pouring concrete within a cavity formed by walls 144 (FIG.4) of the valve body 108.

In some embodiments, the moment of inertia of the valve body 108 aboutthe axis 112 is maximized by radially displacing the material of thevalve body away from the axis 112. The central portion of the valve body108 near the axis 112 may be removed to increase the moment of inertiaof the valve body 108, as shown in FIG. 4.

It is understood that the exemplary valve body rotator 114 describedwith reference to FIGS. 4-9 is merely one of many forms that the valvebody rotator 114 can have. Additional exemplary embodiments of the valvebody rotator 114 include a screw-like design, in which a componentattached to the shaft 122 is forced to follow a guide surface thatdrives rotation of the valve body 108 about the axis 112 as the valvebody 108 moves along the axis 112. This may take the form of a screw andthread arrangement between the shaft 122 and the conduit 102. Forinstance, the shaft 122 may comprise a lead screw, which is receivedwithin a threaded bore having a fixed location relative to the conduit102. As the valve body 108 moves along the axis 112, the lead screw isforced to rotate due to the engagement with the threaded bore. Otherarrangements are also possible to form the desired valve body rotator114.

It is understood by those skilled in the art that the pressure reliefvalve 106 formed in accordance with one or more embodiments describedherein may also be applied to applications other than burners.Accordingly, some embodiments of the invention are directed to one ormore embodiments of the pressure relief valve 106 alone and incombination with gas flow conduit or a housing 102. Thus, someembodiments of the invention are directed to a pressure relief valve orgas flow regulator 106 comprising the valve body 108 and the valve bodyrotator 114 in accordance with one or more embodiments described herein.The pressure relief valve 106 may be installed in any suitable conduitor housing 102 to provide pressure relief when the pressure within theconduit or housing 102 exceeds a cracking pressure of the valve 106.

Thus, some embodiments of the invention are directed to a pressurerelief valve 106 comprising a valve body 108 configured to engage avalve seat 110 and move along an axis 112 relative to the valve seat 110in response to a pressure within a conduit or housing 102, to which thepressure relief valve 106 is mounted or installed. The valve bodyrotator 114 is configured to rotate the valve body 108 about the axis112 in response to movement of the valve body 108 along the axis 112relative to the valve seat 110. Embodiments described above with regardto the valve body 108 and the valve body rotator 114 may also be appliedto this embodiment of the pressure relief valve 106.

Some embodiments of the invention are directed to a method of regulatinga flow of gas through conduit 102 using the pressure relief valve 106 inaccordance with one or more embodiments described herein. FIG. 10 is aflowchart illustrating a method of regulating a flow of a combustiblegas through an outlet 110 of conduit 102 of a burner in accordance withembodiments of the invention.

At 150 of the method, a valve body 108 is moved along an axis 112relative to a valve seat 110 located at the outlet 104 in response tochanges in pressure or the gas flow at the outlet. At 152, the valvebody 108 is rotated about the axis 112 responsive to the movement of thevalve body 108 along the axis 112 using a valve body rotator 114.

In some embodiments of the method, the valve body 108 engages the valveseat 110 when the pressure at the outlet 104 is below a thresholdpressure. In some embodiments, the valve body 108 is displaced along theaxis 112 from the valve seat 110 when the pressure at the outlet 104 isabove the threshold pressure.

In some embodiments of the method, combustible gas 107 is dischargedthrough the outlet 104 at a substantially constant velocity when thevalve body 108 is displaced from the valve seat 110 and the pressure atthe outlet is above the threshold pressure, as shown in FIG. 2. In someembodiments of the method, the combustible gas 107 is discharged throughan opening formed between the valve body 108 and the valve seat 110 atthe outlet 104, and is ignited using a pilot burner 143.

In some embodiments of the method, an amount of rotation of the valvebody 108 per unit length of movement of the valve body 108 along theaxis 112 relative to the valve seat 110 is based on a distance 119 thevalve body 108 is displaced from the valve seat 110, using the valvebody rotator 114.

In some embodiments of the method, the burner 100 comprises a shaft 122attached to the valve body 108, one or more bushing supports 120 eachhaving a fixed position relative to the conduit or housing 102, and oneor more bushings 121, through which the shaft 122 extends. In someembodiments, each bushing 121 is supported by one of the bushingsupports 120 and is configured to maintain the shaft 122 in generalcoaxial alignment with the axis 112.

In some embodiments, the valve body rotator 114 comprises a rod 126having a first end 128 coupled to the shaft 122 and a second end 132coupled to one of the bushing supports 120 or the conduit or housing102. In some embodiments, the rotating step 152 comprises drivingrotation of the valve body 108 and the shaft 122 about the axis 112using the rod 126 responsive to the moving step 150. In someembodiments, the rod 126 is placed at an angle 138 (FIG. 7) relative tothe axis 112. In some embodiments, the method comprises changing theangle 138 responsive to the moving step 150.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A combustible gas burner comprising: gas flowconduit including an outlet; and a pressure relief valve comprising: avalve seat at the outlet; a valve body configured to engage the valveseat and move along an axis relative to the valve seat in response to apressure at the outlet to regulate a flow of combustible gas through theoutlet; and a valve body rotator configured to rotate the valve bodyabout the axis in response to movement of the valve body along the axisrelative to the valve seat.
 2. The burner according to claim 1, wherein:the valve body engages the valve seat to place the pressure relief valvein a closed mode when the pressure at the outlet is below a thresholdpressure; and pressure-driven movement of the valve body along the axisdisplaces the valve body from the valve seat to place the pressurerelief valve in an open mode when the pressure at the outlet is abovethe threshold pressure.
 3. The burner according to claim 2, whereincombustible gas is discharged through the outlet at a substantiallyconstant velocity when the pressure relief valve is in the open mode. 4.The burner according to claim 2, wherein the valve body rotator iswithin the conduit.
 5. The burner according to claim 1, wherein thevalve body rotator is configured to accelerate the rotation of the valvebody about the axis in response to fluctuations in the pressure at theoutlet.
 6. The burner according to claim 1, wherein the valve bodyrotator is configured to vary an amount of rotation of the valve bodyper unit length of movement of the valve body along the axis relative tothe valve seat based on a distance the valve body is displaced from thevalve seat.
 7. The burner according to claim 6, wherein: the valve bodyrotator is configured to decrease the amount of rotation of the valvebody per unit length of movement of the valve body along the axisrelative to the valve seat as the distance the valve body is displacedfrom the valve seat increases; and the valve body rotator is configuredto increase the amount of rotation of the valve body per unit length ofmovement of the valve body along the axis relative to the valve seat asthe distance the valve body is displaced from the valve seat decreases.8. The burner according to claim 1, wherein the burner comprises: ashaft attached to the valve body; one or more bushing supports, eachhaving a fixed position relative to the conduit; and one or morebushings, through which the shaft extends, each bushing supported by oneof the bushing supports and configured to maintain the shaft in generalalignment with the axis.
 9. The burner according to claim 8, wherein theburner comprises at least two bushing supports displaced from each otheralong the axis.
 10. The burner according to claim 9, wherein the bushingsupports are each attached to the conduit.
 11. The burner according toclaim 8, wherein: the valve body rotator comprises a rod having a firstend coupled to the shaft and a second end coupled to one of the bushingsupports; and the rod drives rotation of the shaft and the valve bodyresponsive to movement of the valve body along the axis relative to thevalve seat.
 12. The burner according to claim 11, wherein: the rod isplaced at an angle relative to the axis; and the angle changes inresponse to movement of the valve body along the axis relative to thevalve seat.
 13. The burner according to claim 1, further comprising apilot burner configured to ignite the combustible gas discharged throughthe outlet.
 14. A method of regulating a flow of combustible gas throughan outlet of conduit or a housing of a burner comprising steps of:moving a valve body along an axis relative to a valve seat located atthe outlet in response to changes in pressure at the outlet; androtating the valve body about the axis responsive to the moving stepusing a valve body rotator.
 15. The method according to claim 14,further comprising: engaging the valve seat with the valve body when thepressure at the outlet is below a threshold pressure; and displacing thevalve body along the axis from the valve seat when the pressure at theoutlet is above the threshold pressure.
 16. The method according toclaim 15, further comprising discharging the combustible gas through theoutlet at a substantially constant velocity when the valve body isdisplaced from the valve seat and the pressure at the outlet is abovethe threshold pressure.
 17. The method according to claim 16, furthercomprising igniting the combustible gas discharged through the outletusing a pilot burner.
 18. The method according to claim 14, furthercomprising varying an amount of rotation of the valve body per unitlength of movement of the valve body along the axis relative to thevalve seat based on a distance the valve body is displaced from thevalve seat using the valve body rotator.
 19. The method according toclaim 14, wherein: the burner comprises: a shaft attached to the valvebody; one or more bushing supports, each having a fixed positionrelative to the conduit; and one or more bushings, through which theshaft extends, each bushing supported by one of the bushing supports andconfigured to maintain the shaft in general alignment with the axis; thevalve body rotator comprises a rod having a first end coupled to theshaft and a second end coupled to one of the bushing supports; and therotating step comprises driving rotation of the valve body and the shaftabout the axis using the rod responsive to the moving step.
 20. Themethod according to claim 19, wherein: the rod is placed at an anglerelative to the axis; and the method comprises changing the angleresponsive to the moving step.